diff --git a/cv5/a_train.c b/cv5/a_train.c
index 570c209..b6d2b6a 100644
--- a/cv5/a_train.c
+++ b/cv5/a_train.c
@@ -11,6 +11,9 @@ struct car* add_car(struct car* first,const char* target) {
     if(first == NULL){
         return newcar;
     }
+    if(target == NULL){
+        return NULL;
+    }
     struct car *this = first;
     while(this->next != NULL){
         this = this->next;